With rapid development of communications technologies, in a communications network the requirements for system capacity, data throughput rate, transmission delay, and transmission reliability are increasingly high. However, bandwidth that a traditional microwave frequency band can provide is limited, which cannot meet ever-increasing requirements, and therefore mobile communication will inevitably develop into a millimeter wave band with a higher frequency band. Currently, advantages of millimeter wave (high frequency) communication are a large capacity and a high data throughput rate. However, because of the atmosphere, water mist/vapor, and obstructions, attenuation of the millimeter wave communication is high, and generally, coverage of a high-frequency base station is relatively small. In addition, in high-frequency networking communication, because a millimeter wave may be easily affected by environment interference, for example, a factor such as an architectural blockage, a human body blockage, or interference, a coverage hole appears at a specific probability in a coverage area of a high-frequency base station, wherein a signal received by user equipment (UE) is very weak and even cannot be effectively demodulated.
In the prior art, a multi-level beam switching mechanism is mainly introduced to resolve the foregoing technical problem, thereby ensuring reliability of high-frequency communication. Specifically, an operating principle of the multi-level beam switching mechanism is mainly as follows: In a case of high-low frequency hybrid networking, UE may receive many beams from a same base station or from different base stations, and after selecting a beam with best signal quality to access a link, the UE still periodically measures a signal of another beam that can be received, and prioritizes target beams satisfying a link that can be accessed, where priority orders may be as follows: (1) corresponding to a control channel as that of a currently accessed beam; (2) corresponding to a control channel different from that of the currently accessed beam, but connected to a same cell; (3) connected to a cell different from that of the currently accessed beam, but connected to a same cellular base station; (4) connected, in a wired manner, to a cellular base station different from that connected to the currently accessed beam; (5) connected, in a wireless manner, to a cellular base station different from that connected to the currently accessed beam. When communication quality of the accessed beam deteriorates and even communication is disconnected, the UE first attempts to recover the communication quality of the current beam, and if the communication quality cannot be recovered, switches to another target beam according to the foregoing priority orders to maintain communication continuity.
However, in the prior art, when UE enters a coverage hole because of blockage of an obstruction or other interference, a link is suddenly disconnected or deteriorates into a state in which normal demodulation cannot be performed, and in this case, there is no beam that can be switched, or when a beam that can be used for switching is blocked by an obstruction or is affected by other interference, signal quality deteriorates into a state in which normal receiving cannot be performed, high-frequency communication is disconnected, which still causes a problem of relatively low system reliability.